1. Field of the Invention
The present invention relates to a laser markable laminated sheet and, more particularly, to a sheet having a transparent laminate adhered over a thermally printable sheet.
2. Description of the Related Art
Product marking devices are known which employ the heat of a laser beam. With such devices, a controlled laser beam burns a product code, date, or the like, into the surface of a label, or directly into the surface of the product container or container closure. In a typical laser marking application, a white or light colored paper product carton or box has a rectangular area coated with a dark ink. The laser beam is directed on the dark ink and controlled with a mask so as to burn away the dark ink in selected areas to expose the white surface beneath the ink and thus form the desired markings. A suitable laser marking system for such an application is the "Blazer 6000" laser marking system sold by Lasertechnics of Albuquerque, N.M.
A laser marking system of the type described above is subject to significant disadvantages. The design of the product container or label must include an area coated with a dark, contrasting ink. This adds a step of printing, and may conflict with the desire to have a predominately white or light colored package. Furthermore, the burned-away ink becomes airborne particles which must be captured in order to prevent contamination of the products, the containers, and the packaging equipment. Such airborne particles are particularly objectionable in a clean environment such as that of a pharmaceutical laboratory or factory.